Transmission for a Motor Vehicle

ABSTRACT

A transmission (G) for a motor vehicle includes an electric machine (EM 1 ), a first input shaft (GW 1 ), a second input shaft (GW 2 ), an output shaft (GWA), three planetary gear sets (P 1 , P 2 , P 3 ), and at least six shift elements (A, B, C, D, E, F). Different gears are implementable by selectively actuating the at least six shift elements (A, B, C, D, E, F) and, in addition, in interaction with the electric machine (EM 1 ), different operating modes are implementable. A drive train for a motor vehicle with such a transmission (G) and to a method for operating same are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related and has right of priority to GermanPatent Application No. 102018217859.3 filed in the German Patent Officeon Oct. 18, 2018 and is a nationalization of PCT/EP2019/074643 filed inthe European Patent Office on Sep. 16, 2019, both of which areincorporated by reference in their entirety for all purposes.

FIELD OF THE INVENTION

The invention relates generally to a transmission for a motor vehicle,including an electric machine. Moreover, the invention relates generallyto a motor vehicle drive train, in which an aforementioned transmissionis utilized, and to a method for operating a transmission.

BACKGROUND

In the case of hybrid vehicles, transmissions are known which alsoinclude, in addition to a gear set, one or multiple electric machine(s).In this case, the transmission is usually configured to be multi-stage,i.e., multiple different ratios are selectable, as gears, between aninput shaft and an output shaft by actuating appropriate shift elements,wherein this is preferably automatically carried out. Depending on thearrangement of the shift elements, the shift elements are clutches oralso brakes. The transmission is utilized in this case for suitablyimplementing an available tractive force of a prime mover of the motorvehicle with respect to various criteria. In this case, the gears of thetransmission are mostly also utilized in interaction with the at leastone electric machine for implementing purely electric driving.Frequently, the at least one electric machine can also be integrated inthe transmission in order to implement various operating modes indifferent ways.

DE 10 2014 218 610 A1 describes a transmission for a hybrid vehicle,which includes, in addition to a first input shaft and an output shaft,three planetary gear sets and an electric machine. Moreover, in onevariant, six shift elements are provided, via which different powerpaths are achieved from the first input shaft to the output shaft whileimplementing different gears and, in addition, different integrations ofthe electric machine can be configured. Here, purely electric drivingcan also be implemented simply by transmitting power via the electricmachine.

BRIEF SUMMARY OF THE INVENTION

Example aspects of the present invention provide an alternativeembodiment of the transmission for a motor vehicle known from the priorart, with which, with a compact design, different operating modes can beimplemented in a suitable way.

According to example aspects of the invention, a transmission includesan electric machine, a first input shaft, a second input shaft, anoutput shaft, as well as a first planetary gear set, a second planetarygear set, and a third planetary gear set. The planetary gear setsinclude multiple elements, wherein, preferably, a first element, asecond element, and a third element are associated with each of theplanetary gear sets. In addition, a first shift element, a second shiftelement, a third shift element, a fourth shift element, a fifth shiftelement, and a sixth shift element are provided, via the selectiveactuation of which different power paths can be implemented whileshifting different gears. It is particularly preferred when at leastfour different gears can be formed, by the ratio, between the firstinput shaft and the output shaft. Moreover, a rotor of the electricmachine is connected to the second input shaft.

Within the meaning of the invention, a “shaft” is understood to be arotatable component of the transmission, via which associated componentsof the transmission are rotationally fixed to each other or via which aconnection of this type is established upon actuation of an appropriateshift element. The particular shaft can connect the components to eachother axially or radially or also both axially and radially. Theparticular shaft can also be present as an intermediate piece, via whicha particular component is connected, for example, radially.

Within the meaning of the invention, “axially” means an orientation inthe direction of a longitudinal central axis, along which the planetarygear sets are arranged coaxially to one another. “Radially” is thenunderstood to mean an orientation in the direction of the diameter of ashaft that lies on this longitudinal central axis.

Preferably, the output shaft of the transmission includes a toothsystem, via which the output shaft is then operatively connected, in themotor vehicle drive train, to a differential gear arranged axiallyparallel to the output shaft. In this case, the tooth system ispreferably provided at a mounting interface of the output shaft, whereinthis mounting interface of the output shaft is preferably situatedaxially in the area of an end of the transmission, at which a mountinginterface of the first input shaft is also provided, the mountinginterface establishing the connection to the upstream prime mover. Thistype of arrangement is particularly suitable for the application in amotor vehicle with a drive train aligned transversely to the directionof travel of the motor vehicle.

Alternatively, an output of the transmission can also be provided, inprinciple, at an axial end of the transmission situated opposite to amounting interface of the first input shaft. In this case, a mountinginterface of the output shaft is then designed at an axial end of theoutput shaft coaxially to a mounting interface of the first input shaft,so that the input and the output of the transmission are located atopposite axial ends of the transmission. A transmission configured inthis way is suitable for the application in a motor vehicle with a drivetrain aligned in the direction of travel of the motor vehicle.

According to a first example variant of the invention, the planetarygear sets are arranged in the sequence first planetary gear set, secondplanetary gear set, and, finally, third planetary gear set axiallyfollowing the mounting interface of the first input shaft. According toan alternative, second example variant of the invention, the planetarygear sets follow the mounting interface of the first input shaft in thesequence second planetary gear set, third planetary gear set and,finally, first planetary gear set, however.

Example aspects of the invention now encompasses the technical teachingthat the first input shaft is rotationally fixed to the second elementof the first planetary gear set, while the output shaft is rotationallyfixed to the third element of the first planetary gear set. Moreover,the second input shaft is rotationally fixed to the third element of thesecond planetary gear set, whereas the first element of the secondplanetary gear set is fixed. Moreover, two of the elements of the firstplanetary gear set are connectable to each other in a rotationally fixedmanner via the second shift element, while the first element of thefirst planetary gear set is fixable by the third shift element. Thesecond element of the second planetary gear set is connectable to thefirst input shaft in a rotationally fixed manner via the fourth shiftelement, whereas the first input shaft and the second input shaft areconnected to each other in a rotationally fixed manner by the fifthshift element.

In other words, in the transmission according to example aspects of theinvention, the first input shaft is therefore permanently rotationallyfixed to the second element of the first planetary gear set, while theoutput shaft is permanently connected to the third element of the firstplanetary gear set in a rotationally fixed manner. In addition, thesecond input shaft is permanently rotationally fixed to the thirdelement of the second planetary gear set, and so the electric machine isalso permanently coupled to the third element of the second planetarygear set. In addition, the first element of the second planetary gearset is also permanently fixed and, thereby, permanently prevented frommaking a turning motion.

By engaging the second shift element, two of the elements of the firstplanetary gear set are rotationally fixed to each other, which resultsin an interlock of the first planetary gear set. Actuating the thirdshift element brings about a fixation of the first element of the firstplanetary gear set, and so, consequently, the first element of the firstplanetary gear set is prevented from making a turning motion. The fourthshift element, in the actuated condition, connects the second element ofthe second planetary gear set and the first input shaft to each other ina rotationally fixed manner, whereas an engagement of the fifth shiftelement results in a rotationally fixed connection of the first inputshaft and the second input shaft.

The second shift element, the fourth shift element, and the fifth shiftelement are present as clutches, which, upon actuation, eachsynchronize, if necessary, the particular components of the transmissionjoined directly to the clutches, with respect to turning motions of theparticular components and, thereafter, connect the components to eachother in a rotationally fixed manner. However, the third shift elementis present as a brake, which, upon actuation, fixes the component of thetransmission joined directly thereto and, consequently, prevents thecomponent from making a turning motion.

A particular rotationally fixed connection of the rotatable componentsof the transmission is preferably implemented, according to exampleaspects of the invention, via one or also multiple intermediateshaft(s), which can also be present, in this case, as short intermediatepieces when the components are positioned in a spatially dense manner.Specifically, the components that are permanently rotationally fixed toeach other can each be present either as individual components that arerotationally fixed to each other, or also as single pieces. In thesecond case mentioned above, the particular components and theoptionally present shaft are then formed by one common component,wherein this is implemented, in particular, for the case in which theparticular components are situated spatially close to each other in thetransmission.

In the case of components of the transmission that are rotationallyfixed to each other only upon actuation of a particular shift element, aconnection is also preferably implemented via one or also multipleintermediate shaft(s).

A fixation takes place, in particular, by way of a rotationally fixedconnection to a rotationally fixed component of the transmission, whichis preferably a permanently non-rotating component, preferably a housingof the transmission, a part of such a housing, or a componentrotationally fixed thereto.

Within the meaning of the invention, the “connection” of the rotor ofthe electric machine to the second input shaft of the transmission is tobe understood as a connection of such a type that a constantrotational-speed dependence prevails between the rotor of the electricmachine and the second input shaft.

Overall, a transmission according to example aspects of the invention isdistinguished by a compact design, low component loads, good gearingefficiency, and low losses.

According to one example embodiment of the invention, the sixth shiftelement, upon actuation, rotationally fixes the first element and thesecond element of the third planetary gear set to each other, or thefirst element and the third element of the third planetary gear set toeach other, or the second element and the third element of the thirdplanetary gear set to each other. In addition, the first element of thethird planetary gear set is fixable via the first shift element, whilethe second element of the third planetary gear set is rotationally fixedto the output shaft, and the third element of the third planetary gearset is connected to the second element of the second planetary gear setin a rotationally fixed manner.

In other words, an engagement of the sixth shift element brings aboutthe rotationally fixed connection of two elements of the third planetarygear set, which results in an interlock of the third planetary gear set.Specifically, the sixth shift element, upon actuation, can rotationallyfix the first element and the second element of the third planetary gearset to each other, or the second element and the third element of thethird planetary gear set to each other, or the first element and thethird element of the third planetary gear set to each other. The firstshift element, upon actuation, fixes the first element of the thirdplanetary gear set, however, and so, consequently, this is preventedfrom making a turning motion. In addition, the second element of thethird planetary gear set is permanently rotationally fixed to the outputshaft, while the third element of the third planetary gear set ispermanently connected to the second element of the second planetary gearset in a rotationally fixed manner. In this case, the first shiftelement is present as a brake, while the sixth shift element is designedas a clutch.

According to an alternative example design option of the invention, thesecond element of the second planetary gear set can be rotationallyfixed to the output shaft via the sixth shift element. Moreover, withrespect to the third planetary gear set, there is a first coupling ofthe first element of the third planetary gear set to a rotationallyfixed component, a second coupling of the second element of the thirdplanetary gear set to the output shaft, and a third coupling of thethird element of the third planetary gear set to the second element ofthe second planetary gear set, wherein, of these couplings, twocouplings are present as permanently rotationally fixed connections,while, with respect to the remaining coupling, a rotationally fixedconnection is implementable by the first shift element.

In this example design option of the invention, upon actuation of thesixth shift element, the second element of the second planetary gear setand the output shaft are therefore connected to each other in arotationally fixed manner. In addition, with respect to the thirdplanetary gear set, three couplings are present, of which the firstcoupling is present between the first element of the third planetarygear set and a rotationally fixed component of the transmission, whilethe second coupling is present between the second element of the thirdplanetary gear set and the output shaft, and the third coupling ispresent between the third element of the third planetary gear set andthe second element of the second planetary gear set. Of these couplings,two couplings are designed as permanently rotationally fixedconnections, while, with respect to the remaining coupling, arotationally fixed connection is formed only by engaging the first shiftelement.

Specifically, in a first example variant of the aforementioned designoption, the second element of the third planetary gear set is thereforepermanently rotationally fixed to the output shaft and the third elementof the third planetary gear set is permanently rotationally fixed to thesecond element of the second planetary gear set, whereas the firstelement of the third planetary gear set is fixed by engaging the firstshift element. In this case, the first shift element is present as abrake, while the sixth shift element is designed as a clutch.

Alternatively, the first element of the third planetary gear set ispermanently fixed, wherein the first element of the third planetary gearset can be rotationally fixed to the first element of the secondplanetary gear set. Moreover, the second element of the third planetarygear set is permanently rotationally fixed to the output shaft, whereasthe third element of the third planetary gear set is connected to thesecond element of the second planetary gear set in a rotationally fixedmanner only by engaging the first shift element. The first shift elementand the sixth shift element are each present as a clutch.

According to a further, alternative example variant, the first elementof the third planetary gear set is permanently fixed and can also berotationally fixed to the first element of the second planetary gearset, while the third element of the third planetary gear set ispermanently rotationally fixed to the second element of the secondplanetary gear set and the second element of the third planetary gearset is connected to the output shaft in a rotationally fixed manner onlyby actuating the first shift element. In this case as well, the firstshift element and the sixth shift element are each present as a clutch.

According to one example embodiment of the invention, selectiveengagement of the six shift elements results gears that differ in termsof ratio and an auxiliary gear between the first input shaft and theoutput shaft. A first gear can be implemented between the first inputshaft and the output shaft by actuating the first shift element and thefifth shift element, in which travel takes place with the simultaneousintegration of a prime mover joined at the first input shaft, and theelectric machine. Moreover, a second gear results between the firstinput shaft and the output shaft by engaging the first shift element andthe fourth shift element, wherein travel takes place in this case aswell with the simultaneous integration of the upstream prime mover andthe electric machine.

In addition, a third gear can be implemented between the first inputshaft and the output shaft in a first variant by engaging the firstshift element and the second shift element. In addition, the third gearcan also be selected, in a second variant, by actuating the second andthe sixth shift elements, in a third variant by engaging the fourth andthe sixth shift elements, in a fourth variant by actuating the secondand the fourth shift elements, in a fifth variant by engaging the secondand the fifth shift elements, and in a sixth variant by engaging thesecond shift element. This is the case because the third gear resultsalready by engaging the second shift element, since the first inputshaft and the output shaft are then connected to each other in arotationally fixed manner via the interlocked, first planetary gear set,and so travel can take place via the upstream prime mover. The electricmachine can be decoupled, since, in this case, only the second shiftelement is loaded with torque and, in addition, the second input shaftcan remain idle. As a result, zero-load losses of the electric machinecan be avoided. However, a shift into the first five variants of thethird gear has the advantage that the electric machine is alsointegrated and, as a result, hybrid driving can take place.

In addition, a fourth gear can be implemented between the first inputshaft and the output shaft in a first variant by actuating the firstshift element and the third shift element, wherein the fourth gear alsoresults, in a second variant, by engaging the third shift element andthe sixth shift element, in a third variant by actuating the third shiftelement and the fourth shift element, in a fourth variant by engagingthe third shift element and the fifth shift element, and in a fifthvariant by engaging the third shift element. Once again, in the fifthvariant of the fourth gear, pure travel via the upstream prime mover cantake place, since, when the third shift element is engaged, the firstinput shaft and the output shaft are coupled to each other via the firstplanetary gear set. The electric machine can also be decoupled in thiscase, since, when the third shift element is engaged, only the thirdshift element is loaded with torque and the second input shaft canremain idle. Consequently, zero-load losses of the electric machine canalso be avoided in the fifth variant of the fourth gear. Animplementation of the first four variants of the fourth gear has theadvantage that hybrid driving can take place due to the simultaneousintegration of the upstream prime mover and the electric machine.

Finally, an auxiliary gear results by engaging the fifth shift elementand the sixth shift element.

Given a suitable selection of stationary transmission ratios of theplanetary gear sets, a transmission ratio range which is suitable forthe application in a motor vehicle is implemented as a result. In thiscase, gear shifts between the gears can be implemented, in which onlythe condition of two shift elements, in each case, is always to bevaried, in that one of the shift elements contributing to the precedinggear is to be disengaged and another shift element is to be engaged inorder to implement the subsequent gear. As a further consequencethereof, a shift between the gears can take place very rapidly.

Due to the connection of the electric machine to the second input shaftof the transmission, different operating modes can also be achieved in asimple way.

A first gear between the second input shaft and the output shaft can beutilized for purely electric driving, wherein this first gear results byengaging the first shift element. As a result, the rotor of the electricmachine is coupled to the output shaft via the second planetary gear setand the third planetary gear set, wherein a ratio of this first gearcorresponds to a ratio of the first gear that is effective between thefirst input shaft and the output shaft.

In addition, a second gear can also be implemented between the secondinput shaft and the output shaft for purely electric driving. The sixthshift element is to be actuated in order to implement this second gear,and so the second input shaft and, thereby, also the rotor of theelectric machine are then connected to the output shaft via the secondplanetary gear set. A ratio of this second gear, which is effectivebetween the second input shaft and the output shaft, corresponds to aratio of the auxiliary gear between the first input shaft and the outputshaft.

Starting from purely electric driving in the first gear, which iseffective between the second input shaft and the output shaft, theupstream prime mover can then be started into the first gear, which iseffective between the first input shaft and the output shaft, into thesecond gear, which is effective between the first input shaft and theoutput shaft, into the first variant of the third gear, which iseffective between the first input shaft and the output shaft, or in thefirst variant of the fourth gear, which is effective between the firstinput shaft and the output shaft, since the first shift elementcontributes to each of these.

A start of the upstream prime mover into the second variant and into thethird variant of the third gear, which is effective between the firstinput shaft and the output shaft, into the second variant of the fourthgear, which is effective between the first input shaft and the outputshaft, or into the auxiliary gear can also take place from the secondgear, which is effective between the second input shaft and the outputshaft.

As a further operating mode, a charging operation of an electricaccumulator can also be implemented, in that only the fourth shiftelement is engaged and, thereby, a coupling of the first input shaft tothe second input shaft and, thereby, also to the electric machine isestablished via the second planetary gear set. The second input shaftrotates faster than the first input shaft. At the same time, a force-fitconnection to the output shaft is not established, and therefore thetransmission is in a neutral position. Apart from a charging operation,a start of the upstream prime mover via the electric machine can also beimplemented as a result. Alternatively, a charging or starting operationcan also be implemented by actuating the fifth shift element, however,wherein, in this case, the first input shaft and the second input shaftare directly connected to each other in a rotationally fixed manner. Inthis case as well, a force-fit connection to the output shaft is notestablished, and so charging can be implemented in a problem-free mannerwhen the electric machine is operated as a generator or also startingcan be implemented in a problem-free manner when the electric machine isoperated as an electric motor.

Moreover, powershifts with tractive force support can be implemented.During the gearchange between the first gear, which is effective betweenthe first input shaft and the output shaft, and the second gear, whichis effective between the first input shaft and the output shaft, thetractive force with the first shift element engaged can be supported viathe electric machine, wherein the synchronization of the shift elementto be engaged takes place via a closed-loop control of the rotationalspeed of the upstream prime mover. Alternatively, however, this can alsotake place by using synchronized shift elements or also by usinganother, separate synchronizing mechanism, such as a transmission brakeor also one further electric machine, which can be operatively connecteddirectly or indirectly to the first input shaft. If one further shiftelement, as a separating clutch, is also provided on the input side ofthe input shaft, the inertial mass of the upstream drive machine can bedecoupled during the synchronization.

A gearchange under load can also take place between the second gear,which is effective between the first input shaft and the output shaft,and the first variant of the third gear, which is effective between thefirst input shaft and the output shaft, with the first shift elementengaged. This is also implementable, in addition, during a gearchangebetween the first variant of the third gear, which is effective betweenthe first input shaft and the output shaft, and the first variant of thefourth gear, which is effective between the first input shaft and theoutput shaft, since the first shift element contributes to each of thetwo variants in this case as well.

The transmission according to example aspects of the invention can alsobe operated in such a way that a rotational-speed reduction of theelectric machine is achieved during driving. It is therefore possible toinitially drive in a hybrid manner in the first variant of the fourthgear, in that the first shift element initially remains engaged eitherafter a gear shift from the third gear into the fourth gear with torqueassistance from the electric machine or after a start of the prime moverinto the fourth gear. In order to now reduce a rotational speed of theelectric machine in the fourth gear at higher ground speeds, however, achange-over can be carried out from the first variant of the fourth gearinto the second variant of the fourth gear, since the rotor of theelectric machine has a lower rotational speed here than in the firstvariant of the fourth gear. This change-over takes place while obtainingthe tractive force via the upstream prime mover, with the third shiftelement engaged. Initially, the load-free, first shift element isdisengaged and, subsequent thereto, the load-free, sixth shift elementis engaged, wherein the rotational-speed adaptation takes place viaclosed-loop control of the rotational speed of the electric machine.

A separate shift element is not necessary for decoupling the upstreamprime mover, since, in the second variant of the fourth gear, which iseffective between the first input shaft and the output shaft, theupstream prime mover can be decoupled by disengaging the third shiftelement. As a result, the second gear is then implemented, which iseffective between the second input shaft and the output shaft. Inaddition, in the case of a vehicle that is slowing down, a downshiftfrom the fourth gear, which is effective between the first input shaftand the output shaft, into the third gear, which is effective betweenthe first input shaft and the output shaft, can be prepared, in that,initially, a change-over takes place from the second variant into thefirst variant of the fourth gear and, in the process, the tractive forceis obtained via the upstream prime mover, with the third shift elementengaged. In the first variant of the fourth gear, the first shiftelement is engaged, which becomes necessary in order to support thetractive force via the electric machine as part of the downshift fromthe fourth gear into the third gear.

Alternatively, a downshift from the fourth gear, which is effectivebetween the first input shaft and the output shaft, into the third gear,which is effective between the first input shaft and the output shaft,can also be implemented with the sixth shift element engaged, however,in that a change-over takes place between the second variant of thefourth gear and the second variant of the third gear, to theimplementation of which the sixth shift element contributes, in eachcase. The electric machine then supports the tractive force. Thereafter,the sixth shift element can be disengaged, if necessary, and,subsequently, the first shift element can be engaged, wherein asynchronization takes place via the electric machine and a support ofthe tractive force takes place via the upstream prime mover. As aresult, the rotational speed of the electric machine can also be variedin the third gear, which is effective between the first input shaft andthe output shaft.

As one further example design option of the invention, a furtherelectric machine is provided, the rotor of which is connected at thefirst input shaft. Such an example embodiment has the advantage thatfurther driving modes can be achieved as a result. In addition, as aresult, a start of the upstream prime mover can be implementedimmediately, if necessary, if the prime mover is designed as an internalcombustion engine. In addition, the additional electric machine cansupport the upstream prime mover in the synchronization of shiftelements.

According to one further example embodiment of the invention, the firstinput shaft can be connected in a rotationally fixed manner, via aseventh shift element, to a connection shaft, which, in turn, is thenpreferably coupled within a motor vehicle drive train to the prime moverconnected upstream from the transmission. The seventh shift element canbe designed, in principle, as a force-locking or also as a form-lockingshift element in this case, although it is particularly preferred whenthe seventh shift element is present as a dog clutch. Via the seventhshift element, the upstream prime mover can therefore also be completelydecoupled from the transmission, so that a purely electric operation isimplementable in a problem-free manner.

According to a further example design option of the invention, the firstinput shaft can be rotationally fixed to the first element of the thirdplanetary gear set via a further shift element. As a result, a startingfunction for forward travel can be implemented when driving via thefirst input shaft. The upstream prime mover is connected to the firstelement of the third planetary gear set via the further shift element,while the electric machine is connected to the third element of thethird planetary gear set via the constant ratio of the second planetarygear set and the connection to the output shaft is established via thesecond element of the third planetary gear set. In this startingfunction, a ratio for the upstream prime mover results, which is higherthan the ratio of the first gear that is effective between the firstinput shaft and the output shaft. The starting function thereforeexpands the overall gear ratio. The aforementioned example design optioncan only be implemented in the transmission according to example aspectsof the invention, however, when the planetary gear sets are arranged inthe sequence second planetary gear set, third planetary gear set, and,finally, first planetary gear set.

In one example refinement of the invention, one or multiple shiftelement(s) is/are each implemented as a form-locking shift element. Inthis case, the particular shift element is preferably designed either asa constant-mesh shift element or as a lock-synchronizer mechanism.Form-locking shift elements have the advantage over friction-lockingshift elements that lower drag losses occur in the disengaged condition,and therefore a better efficiency of the transmission can be achieved.In particular, in the transmission according to example aspects of theinvention, all shift elements are implemented as form-locking shiftelements, and therefore the lowest possible drag losses can be achieved.Preferably, the seventh shift element, which is provided, if necessary,and the further shift element are both designed as force-locking shiftelements. In principle, however, one shift element or multiple shiftelements could also be configured as force-locking shift elements, forexample, as lamellar shift elements.

Within the scope of example aspects of the invention, the planetary gearsets can each be present as a negative or minus planetary gear set,provided it allows for a connection of the elements, wherein the firstelement of the particular planetary gear set is a sun gear, the secondelement of the particular planetary gear set is a planet carrier, andthe third element of the particular planetary gear set is a ring gear. Aminus planetary gear set is composed, in a way known, in principle, to aperson skilled in the art, of the elements sun gear, planet carrier, andring gear, wherein the planet carrier, rotatably mounted, guides atleast one planet gear, although preferably multiple planet gears, whicheach individually intermesh with the sun gear and with the surroundingring gear.

Alternatively thereto, one planetary gear set or even both planetarygear sets could also be present as a positive or plus planetary gearset, however, provided the connection of the particular elements permitsthis, wherein the first element of the particular planetary gear set isa sun gear in this case, the second element of the particular planetarygear set is a ring gear, and the third element of the particularplanetary gear set is a planet carrier. In a plus planetary gear set aswell, the elements sun gear, ring gear, and planet carrier are present,wherein the latter guides at least one planet gear pair, in which oneplanet gear is meshed with the internal sun gear and the other planetgear is meshed with the surrounding ring gear, and the planet gears areintermeshed with each other.

Where permitted by a connection of the individual elements, a minusplanetary gear set can be converted into a plus planetary gear set,wherein, as compared to the design as a minus planetary gear set, thering gear connection and the planet carrier connection are to beinterchanged, and a stationary transmission ratio is to be increased byone. Conversely, a plus planetary gear set could also be replaced by aminus planetary gear set, provided the connection of the elements of thetransmission enables this. In this case, as compared to the plusplanetary gear set, the ring gear connection and the planet carrierconnection would also need to be interchanged, and a stationarytransmission ratio would need to be reduced by one. Within the scope ofexample aspects of the invention, the three planetary gear sets are eachpreferably designed as a minus planetary gear set, however.

According to one further example embodiment of the invention, the firstshift element and the sixth shift element are combined to form a shiftelement pair, with which one actuating element is associated. The firstshift element, on the one hand, and the sixth shift element, on theother hand, can be actuated via the actuating element starting from aneutral position. This has the advantage that, due to this combination,the number of actuating elements can be reduced and, thereby, themanufacturing complexity can also be reduced.

Alternatively or also in addition to the aforementioned examplevariants, the second shift element and the third shift element arecombined to form a shift element pair, with which one actuating elementis associated. The second shift element, on the one hand, and the thirdshift element, on the other hand, can be actuated from a neutralposition via this actuating element. As a result, the manufacturingcomplexity can be reduced, in that, due to the combination of the twoshift elements to form a shift element pair, one actuating unit can beutilized for both shift elements.

In addition, alternatively or also in addition to the two aforementionedexample variants, the fourth shift element and the fifth shift elementare combined to form a shift element pair, with which one actuatingelement is associated. The fourth shift element, on the one hand, andthe fifth shift element, on the other hand, can be actuated via thisactuating element starting from a neutral position. As a result of thisas well, the manufacturing complexity can be reduced, since an actuationof the two shift elements can therefore take place via one commonactuating unit.

It is particularly preferred, however, when all three aforementionedshift element pairs are implemented, and so the six shift elements ofthe transmission can be actuated via three actuating elements. As aresult, a particularly low manufacturing complexity can be achieved.

According to one example embodiment of the invention, the rotor of theelectric machine is rotationally fixed to the second input shaft.Alternatively, according to one example design option of the invention,the rotor is connected to the second input shaft via at least one gearstage. The electric machine can be arranged either coaxially to theplanetary gear sets or so as to be situated axially offset with respectthereto. In the former case, the rotor of the electric machine caneither be rotationally fixed directly to the second input shaft or canbe coupled thereto via one or also multiple intermediate gear stage(s),wherein the latter allows for a more favorable configuration of theelectric machine with higher rotational speeds and lower torques. The atleast one gear stage can be designed as a spur gear stage and/or as aplanetary gear stage in this case. In the case of a coaxial arrangementof the electric machine, at least two of the planetary gear sets canthen also, more preferably, be arranged axially in the area of theelectric machine as well as radially internally with respect thereto, sothat the axial installation length of the transmission can be shortened.

If the electric machine is provided axially offset with respect to theplanetary gear sets, however, a coupling takes place via one or multipleintermediate gear stage(s) and/or a flexible traction drive mechanism.The one or the multiple gear stage(s) can also be implementedindividually, in this case, either as a spur gear stage or as aplanetary gear stage. A flexible traction drive mechanism can be eithera belt drive or a chain drive.

If a further electric machine is also provided, a rotor of this furtherelectric machine can also be either rotationally fixed to the firstinput shaft directly or can be coupled to the first input shaft via atleast one gear stage. The at least one gear stage can be a spur gearstage or a planetary gear stage or also a flexible traction drivemechanism. In addition, the further electric machine can be providedcoaxially or also axially offset with respect to the first input shaftand, thereby, also to the planetary gear sets.

Within the scope of example aspects of the invention, a startingcomponent can be installed upstream from the transmission, for example ahydrodynamic torque converter or a friction clutch. This startingcomponent can then also be an integral part of the transmission and actsto configure a starting process, in that the starting component enablesa slip speed between the prime mover, which is designed, in particular,as an internal combustion engine, and the first input shaft of thetransmission. In this case, one of the shift elements of thetransmission or the separating clutch, which may be present, can also bedesigned as such a starting component, in that it is present as africtional shift element. In addition, a one-way clutch with respect tothe transmission housing or to another shaft can be arranged on eachshaft of the transmission, in principle.

The transmission according to the invention is, in particular, part of amotor vehicle drive train for a hybrid or electric vehicle and is thenarranged between a prime mover of the motor vehicle, which is configuredas an internal combustion engine or as an electric machine, and furthercomponents of the drive train, which are arranged downstream in thedirection of power flow to driving wheels of the motor vehicle. In thiscase, the first input shaft of the transmission is either permanentlycoupled to a crankshaft of the internal combustion engine or to therotor shaft of the electric machine in a rotationally fixed manner or isconnectable thereto via an intermediate separating clutch or a startingcomponent, wherein a torsional vibration damper can also be providedbetween an internal combustion engine and the transmission. On theoutput end, the transmission is then preferably coupled, within themotor vehicle drive train, to a differential gear of a drive axle of themotor vehicle, wherein a connection to an interaxle differential canalso be present in this case, however, via which a distribution tomultiple driven axles of the motor vehicle takes place. The differentialgear or the interaxle differential can be arranged with the transmissionin one common housing in this case. A torsional vibration damper, whichis optionally present, can also be integrated into this housing.

Within the meaning of the invention, the expressions that two componentsof the transmission are “connected” or “coupled” or “are connected toeach other” mean a permanent coupling of these components, and thereforesaid components cannot rotate independently of each other. In thatrespect, no shift element is provided between these components, whichcan be elements of the planetary gear sets and/or also shafts and/or arotationally fixed component of the transmission. Instead, theappropriate components are coupled to each other with a consistentrotational speed dependence.

However, if a shift element is provided between two components, thesecomponents are not permanently coupled to each other. Instead, acoupling is carried out only by actuating the intermediate shiftelement. In this case, an actuation of the shift element means, withinthe meaning of the invention, that the particular shift element istransferred into an engaged condition and, consequently, synchronizesthe turning motions, if necessary, of the components connected directlythereto. In the case of an embodiment of the particular shift element asa form-locking shift element, the components directly connected to eachother in a rotationally fixed manner via the shift element rotate at thesame rotational speed, while, in the case of a force-locking shiftelement, speed differences can exist between the components also afteran actuation of the same shift element. This intentional or alsounintentional condition is nevertheless referred to, within the scope ofthe invention, as a rotationally fixed connection of the particularcomponents via the shift element.

The invention is not limited to the specified combination of features ofthe main claim or the claims dependent thereon. In addition, individualfeatures can be combined with one another, provided they arise from theclaims, the description of preferred embodiments of the invention whichfollows, or directly from the drawings. References in the claims to thedrawings via the use of reference signs is not intended to limit thescope of protection of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantageous embodiments of the invention, which are explained in thefollowing, are represented in the drawings, in which:

FIG. 1 shows a diagrammatic view of a motor vehicle drive train;

FIGS. 2 through 12 each show a diagrammatic view of a transmission ofthe type that can be utilized in the motor vehicle drive train from FIG.1;

FIG. 13 shows an exemplary shift pattern of the transmissions from FIGS.2 to 12;

FIGS. 14 and 15 each show a diagrammatic view of a transmission of thetype that can also be utilized in the motor vehicle drive train fromFIG. 1;

FIG. 16 shows a representation in table form of different conditions ofthe motor vehicle drive train from FIG. 1 with a transmission accordingto FIG. 14 or 15;

FIGS. 17 through 22 each show a schematic of a modification of thetransmissions from FIGS. 2 through 12 as well as 14 and 15.

DETAILED DESCRIPTION

Reference will now be made to embodiments of the invention, one or moreexamples of which are shown in the drawings. Each embodiment is providedby way of explanation of the invention, and not as a limitation of theinvention. For example, features illustrated or described as part of oneembodiment can be combined with another embodiment to yield stillanother embodiment. It is intended that the present invention includethese and other modifications and variations to the embodimentsdescribed herein.

FIG. 1 shows a diagrammatic view of a motor vehicle drive train of ahybrid vehicle, wherein, in the motor vehicle drive train, an internalcombustion engine VKM is connected to a transmission G via anintermediate torsional vibration damper TS. Connected downstream fromthe transmission G, on the output end thereof, is a differential gearAG, via which drive power is distributed to driving wheels DW of a driveaxle of the motor vehicle. The transmission G and the torsionalvibration damper TS are arranged in a common housing of the transmissionG in this case, into which the differential gear AG can then also beintegrated. As is also apparent in FIG. 1, the internal combustionengine VKM, the torsional vibration damper TS, the transmission G, andalso the differential gear AG are aligned transversely to a direction oftravel of the motor vehicle.

FIG. 2 shows a schematic of the transmission G according to a firstembodiment of the invention. As is apparent, the transmission G iscomposed of a gear set RS and an electric machine EM1, which are botharranged in the housing of the transmission G. The gear set RS includesthree planetary gear sets P1, P2, and P3, wherein each of the planetarygear sets P1, P2, and P3 includes a first element E11 and E12 and E13,respectively, a second element E21 and E22 and E23, respectively, and athird element E31 and E32 and E33, respectively. The first element E11and E12 and E13 is formed by a sun gear of the planetary gear set P1 andP2 and P3, respectively, while the second element E21 and E22 and E23 ofthe planetary gear set P1 and P2 and P3, respectively, is a planetcarrier, and the third element E31 and E32 and E33 of the planetary gearset P1 and P2 and P3, respectively, is a ring gear.

In the present case, the first planetary gear set P1, the secondplanetary gear set P2, and the third planetary gear set P3 are eachtherefore present as a negative or minus planetary gear set. Theparticular planet carrier thereof guides at least one planet gear in arotatably mounted manner; the planet gear is meshed with the particularradially internal sun gear as well as with the particular radiallysurrounding ring gear. It is particularly preferred, however, whenmultiple planet gears are provided in the first planetary gear set P1,in the second planetary gear set P2, and also in the third planetarygear set P3.

Provided this is permitted by the connection, one or also several of theplanetary gear sets P1 through P3 could also each be designed as apositive or plus planetary gear set, wherein, as compared to the designas a minus planetary gear set, the second element E21 and E22 and E23,respectively, is then formed by the respective ring gear and the thirdelement E31 and E32 and E33, respectively, is formed by the respectiveplanet carrier and, in addition, a respective stationary transmissionratio must be increased by one. In the case of a plus planetary gearset, the planet carrier then guides at least one pair of planet gears ina rotatably mounted manner. One planet gear of said pair of planet gearsis meshed with the radially internal sun gear and one planet gear ismeshed with the radially surrounding ring gear, and the planet gearsintermesh with each other.

As is apparent in FIG. 2, the transmission G includes a total of sixshift elements in the form of a first shift element A, a second shiftelement B, a third shift element C, a fourth shift element D, a fifthshift element E, and a sixth shift element F. The shift elements A, B,C, D, E, and F are each designed as form-locking shift elements and arepreferably present as constant-mesh shift elements. While the thirdshift element C is designed as a brake, the remaining shift elements A,B, D, E, and F are present as clutches.

A first input shaft GW1 of the transmission G is permanentlyrotationally fixed to the second element E21 of the first planetary gearset P1 and is rotationally fixable to the first element E11 of the firstplanetary gear set P1 via the second shift element B, which results inan interlock of the first planetary gear set P1 due to the associatedrotationally fixed connection of the first element E11 and of the secondelements E21 of the first planetary gear set P1. The first element E11of the first planetary gear set P1 is also fixable, by engaging thethird shift element C, at a rotationally fixed component GG, which is,in particular, the transmission housing of the transmission G or aportion of this transmission housing.

As is also apparent in FIG. 2, the first element E12 of the secondplanetary gear set P2 is permanently fixed at the rotationally fixedcomponent GG and, thereby, is permanently prevented from making aturning motion, while the third element E32 of the second planetary gearset P2 is permanently connected to a second input shaft GW2 of thetransmission G. The second input shaft GW2 is permanently connected to arotor R1 of the electric machine EM1 in a rotationally fixed manner,while a stator S1 of the electric machine EM1 is fixed at therotationally fixed component GG. In addition, the second input shaft GW2is rotationally fixable to the first input shaft GW1 by engaging thefifth shift element E.

In addition, the second element E22 of the second planetary gear set P2and the third element E33 of the third planetary gear set P3 arepermanently connected to each other in a rotationally fixed manner and,jointly, is connectable to the first input shaft GW1 in a rotationallyfixed manner via the fourth shift element D. The first element E13 ofthe third planetary gear set P3 is fixable at the rotationally fixedcomponent GG by engaging the first shift element A, wherein, moreover,the first element E13 of the third planetary gear set P3 is rotationallyfixable, via the sixth shift element F, to an output shaft GWA of thetransmission G, which is permanently connected in a rotationally fixedmanner to the third element E31 of the first planetary gear set P1 andto the second element E23 of the third planetary gear set P3. Therefore,the actuation of the sixth shift element F results in an interlock ofthe third planetary gear set P3, since the first element E13 and thesecond element E23 of the third planetary gear set P3 are then connectedto each other in a rotationally fixed manner.

The first input shaft GW1 as well as the output shaft GWA form amounting interface GW1-A and GWA-A, respectively, wherein the mountinginterface GW1-A in the motor vehicle drive train from FIG. 1 is utilizedfor a connection at the internal combustion engine VKM, while thetransmission G is connected at the mounting interface GWA-A to thedownstream differential gear AG. The mounting interface GW1-A of thefirst input shaft GW1 is formed at an axial end of the transmission G,while the mounting interface GWA-A of the output shaft GWA is situatedin the area of the same axial end and, here, is aligned transversely tothe mounting interface GW1-A of the first input shaft GW1. In addition,the first input shaft GW1, the second input shaft GW2, and the outputshaft GWA are arranged coaxially to one another.

The planetary gear sets P1, P2, and P3 are also situated coaxially tothe input shafts GW1 and GW2 and the output shaft GWA, wherein they arearranged in the sequence first planetary gear set P1, second planetarygear set P2, and third planetary gear set P3 axially subsequent to themounting interface GW1-A of the first input shaft GW1. Likewise, theelectric machine EM1 is also located coaxially to the planetary gearsets P1, P2, and P3 and, thereby, also to the input shafts GW1 and GW2and the output shaft GWA, wherein the electric machine EM1 is providedaxially at the level of the second planetary gear set P2 and of thethird planetary gear set P3 and radially surrounding these.

As is also apparent from FIG. 2, the first shift element A and the sixthshift element F are arranged axially between the first planetary gearset P1 and the second planetary gear set P2, wherein, specifically, thefirst shift element A and the sixth shift element F are situated axiallybetween the mounting interface GWA-A of the output shaft GWA and thesecond planetary gear set P2, and the sixth shift element F is situatedaxially adjacent to the mounting interface GWA-A. The sixth shiftelement F and the first shift element A are situated axially directlynext to each other and radially at the same level and are combined toform a shift element pair SP1, in that a common actuating element isassociated with the first shift element A and the sixth shift elementF1, via which the sixth shift element F, on the one hand, and the firstshift element A, on the other hand, can be actuated from a neutralposition.

The second shift element B and the third shift element C are arrangedaxially on a side of the first planetary gear set P1 facing the mountinginterface GW1-A of the first input shaft GW1, wherein the third shiftelement C is situated axially adjacent to the first planetary gear setP1. The second shift element B and the third shift element C are alsolocated axially directly next to each other and radially at the samelevel and include a common actuating element, via which the second shiftelement B, on the one hand, and the third shift element C, on the otherhand, can be actuated from a neutral position. In that respect, thesecond shift element B and the third shift element C are combined toform a shift element pair SP2.

Finally, the fourth shift element D and the fifth shift element E aresituated axially on a side of the third planetary gear set P3 facingaway from the second planetary gear set P2, wherein the fourth shiftelement D is arranged axially between the third planetary gear set P3and the fifth shift element E. The fourth shift element D and the fifthshift element E are combined to form a shift element pair SP3, in thatfourth shift element D and the fifth shift element E are providedaxially directly next to each other and radially essentially at the samelevel and include a common actuating element, via which the fourth shiftelement D, on the one hand, and the fifth shift element E, on the otherhand, can be actuated from a neutral position.

Moreover, FIG. 3 shows a diagrammatic view of a transmission G accordingto a second example design option of the invention, which can also beutilized in the motor vehicle drive train in FIG. 1. This example designoption largely corresponds to the preceding example variant according toFIG. 2, with the difference that a second shift element B, uponactuation, now rotationally fixes the first element E11 of the firstplanetary gear set P1 to the output shaft GWA and, thereby, also to thethird element E31 of the first planetary gear set P1, which results inan interlock of the first planetary gear set P1. Once again, the secondshift element B is combined with the third shift element C to form ashift element pair SP2, wherein the shift elements B and C have nowaxially interchanged the positions as compared to the example variantaccording to FIG. 2, however, in that the second shift element B is nowsituated axially between the third shift element C and the firstplanetary gear set P1. Otherwise, the example design option according toFIG. 3 corresponds to the example variant according to FIG. 2, andtherefore reference is made to the description thereof.

FIG. 4 shows a schematic of a transmission G according to a thirdexample embodiment of the invention, of the type which can also beutilized in the motor vehicle drive train from FIG. 1. This exampleembodiment also essentially corresponds to the example variant accordingto FIG. 2, wherein, in contrast thereto, a second shift element B, uponactuation, now rotationally fixes the first element E11 of the firstplanetary gear set P1 to the output shaft GWA and, thereby, also to thethird element E31 of the first planetary gear set P1. This results in aninterlock of the first planetary gear set P1. In addition, the secondshift element B and the third shift element C are now no longer combinedto form a shift element pair, but rather are present as single shiftelements. While the third shift element C is provided axially betweenthe first planetary gear set P1 and the mounting interface GW1-A of thefirst input shaft GW1, the second shift element B is located axiallybetween the first planetary gear set P1 and the second planetary gearset P2, wherein, specifically, the second shift element B is providedaxially between the first planetary gear set P1 and the mountinginterface GWA-A of the output shaft GWA. For the rest, the exampleembodiment according to FIG. 4 corresponds to the example variantaccording to FIG. 2, and therefore reference is made to the descriptionthereof.

FIG. 5 shows a diagrammatic view of a transmission G according to afourth example design option of the invention, which can also beutilized in the motor vehicle drive train from FIG. 1. This exampledesign option largely corresponds to the example variant according toFIG. 2, with the difference that a sixth shift element F, uponactuation, now rotationally fixes the first element E13 of the thirdplanetary gear set P3 to the second element E22 of the second planetarygear set P2 and the third element E33 of the third planetary gear setP3. Therefore, an engagement of the sixth shift element F results in aninterlock of the third planetary gear set P3. The sixth shift element Fis combined with the first shift element A to form a shift element pairSP1, wherein the first shift element A and the sixth shift element F, inthis case, are provided axially between the second planetary gear set P2and the third planetary gear set P3, however. The first shift element Ais situated axially between the second planetary gear set P2 and thesixth shift element F. Otherwise, the example design option according toFIG. 5 corresponds to the example embodiment according to FIG. 2, andtherefore reference is made to the description thereof.

FIG. 6 shows a schematic of a transmission G according to a fifthexample embodiment of the invention, wherein this example embodiment canalso be utilized in the motor vehicle drive train from FIG. 1. Thisexample embodiment also essentially corresponds to the example variantaccording to FIG. 2, wherein, in contrast thereto, a sixth shift elementF, upon actuation, now rotationally fixes the output shaft GWA to thesecond element E22 of the second planetary gear set P2 and the thirdelement E33 of the third planetary gear set P3. Since this also bringsabout a rotationally fixed connection between the second element E23 ofthe third planetary gear set P3 and the third element E33 of the thirdplanetary gear set P3, this results in an interlock of the thirdplanetary gear set P3. Moreover, the first shift element A and the sixthshift element F are no longer combined to form a shift element pair,since the first shift element A is still located axially between themounting interface GWA-A of the output shaft GWA and the secondplanetary gear set P2, while the sixth shift element F is now arrangedaxially between the second planetary gear set P2 and the third planetarygear set P3. For the rest, the example embodiment according to FIG. 6corresponds to the example variant according to FIG. 2, and thereforereference is made to the description thereof.

Moreover, FIG. 7 shows a schematic of a transmission G according to asixth example design option of the invention, which can also be utilizedin the motor vehicle drive train from FIG. 1. This example design optionessentially corresponds to the preceding example variant according toFIG. 6, wherein, in contrast thereto, the first element E13 of the thirdplanetary gear set P3 is now rotationally fixed to the first element E12of the second planetary gear set P2 and is permanently fixed jointlytherewith. Moreover, the third element E33 of the third planetary gearset P3 is now not permanently rotationally fixed to the second elementE22 of the second planetary gear set P2, but rather is connected theretoin a rotationally fixe manner only by engaging a first shift element A.The first shift element A is arranged jointly with the sixth shiftelement F axially between the second planetary gear set P2 and the thirdplanetary gear set P3, wherein the sixth shift element F, uponactuation, connects the second element E22 of the second planetary gearset P2 and the output shaft GWA to each other in a rotationally fixedmanner. The first shift element A is also combined with the sixth shiftelement F to form a shift element pair SP1 and, specifically, issituated axially between the second planetary gear set P2 and the sixthshift element F. For the rest, the example design option according toFIG. 7 corresponds to the example variant according to FIG. 6, andtherefore reference is made to the description thereof.

Moreover, FIG. 8 shows a diagrammatic view of a transmission G accordingto a seventh example embodiment of the invention. This exampleembodiment can be utilized in the motor vehicle drive train from FIG. 1and largely corresponds to the example variant according to FIG. 6. Thedifference in this case is that the first element E13 of the thirdplanetary gear set P3 is permanently fixed, jointly with the firstelement E12 of the second planetary gear set P2, at the rotationallyfixed component GG, while the second element E23 of the third planetarygear set P3 is now no longer permanently rotationally fixed to theoutput shaft GWA. Rather, a rotationally fixed connection is establishedbetween the output shaft GWA and the second element E23 of the thirdplanetary gear set P3 only by engaging a first shift element A. Thefirst shift element A and the sixth shift element F, via which, uponactuation, a rotationally fixed connection is established between thesecond element E22 of the second planetary gear set P2 and the outputshaft GWA, are combined to form a shift element pair SP1 and areprovided axially on a side of the third planetary gear set P3 facingaway from the second planetary gear set P2. Specifically, the firstshift element A is situated axially adjacent to the third planetary gearset P3, wherein the first shift element A and the sixth shift element Fare jointly arranged axially between the third planetary gear set P3, onthe one side, and the fourth shift element D and the fifth shift elementE on the other side. Otherwise, the example embodiment according to FIG.8 corresponds to the example variant according to FIG. 6, and thereforereference is made to the description thereof.

FIG. 9 shows a schematic of a transmission G according to an eighthexample design option of the invention, which can also be utilized inthe motor vehicle drive train from FIG. 1. This example design optionessentially corresponds to the example variant according to FIG. 2, withthe difference that the planetary gear sets P1, P2, and P3 are nowaxially arranged in a changed sequence. Thus, the mounting interfaceGW1-A of the first input shaft GW1 is initially followed by the secondplanetary gear set P2, then the third planetary gear set P3, and,finally, the first planetary gear set P1. In addition, the shiftelements A and F combined to form the shift element pair SP1 areprovided axially between the mounting interface GW1-A of the first inputshaft GW1 and the second planetary gear set P2, wherein, specifically,the shift elements A and F are situated axially between the mountinginterface GW1-A of the first input shaft GW1 and the mounting interfaceGWA-A of the output shaft GWA. The remaining shift elements B, C, D, andE are located axially on a side of the first planetary gear set P1facing away from the third planetary gear set P3, wherein the fourthshift element D is situated axially adjacent to the first planetary gearset P1, followed, axially, initially by the fifth shift element E, thenthe second shift element B, and, finally, the third shift element C.Once again, the second shift element B and the third shift element C arecombined to form a shift element pair SP2, and the fourth shift elementD and the fifth shift element E are combined to form a shift elementpair SP3. The electric machine EM1 is arranged axially at the level ofthe third planetary gear set P3 and of the first planetary gear set P1and radially surrounding these Otherwise, the example embodimentaccording to FIG. 9 corresponds to the example variant according to FIG.2, and therefore reference is made to the description thereof.

FIG. 10 shows a diagrammatic view of a transmission G according to aninth example design option of the invention. This example design optioncan also be utilized in the motor vehicle drive train in FIG. 1 andlargely corresponds to the example variant according to FIG. 7. Thedifference in this case is that the planetary gear sets P1, P2, and P3,as in the preceding variant according to FIG. 9, are arranged axially inthe sequence second planetary gear set P2, third planetary gear set P3,and, finally, first planetary gear set P1 subsequent to the mountinginterface GW1-A of the first input shaft GW1. While the shift elements Aand F combined to form the shift element pair SP1 are arranged axiallybetween the second planetary gear set P2 and the third planetary gearset P3, the remaining shift elements B, C, D, and E are situated axiallyon a side of the first planetary gear set P1 facing away from the thirdplanetary gear set P3. In this case, the fourth shift element D isprovided axially adjacent to the first planetary gear set P1, wherein,positioned axially subsequent thereto, are, initially, the fifth shiftelement E, then the second shift element B, and, finally, the thirdshift element C. As in the variant according to FIG. 9, the fourth shiftelement D and the fifth shift element E are combined to form the shiftelement pair SP3, and the second shift element B and the third shiftelement C are combined to form the shift element pair SP2. Likewise, theelectric machine EM1 is also arranged axially at the level of the thirdplanetary gear set P3 and of the first planetary gear set P1 andradially surrounding these For the rest, the example embodimentaccording to FIG. 10 corresponds to the example variant according toFIG. 7, and therefore reference is made to the description thereof.

Moreover, FIG. 11 shows a schematic of a transmission G according to atenth example embodiment of the invention, of the type which can also beutilized in the motor vehicle drive train in FIG. 1. This exampleembodiment essentially to the example variant according to FIG. 8,wherein, in contrast thereto, the planetary gear sets P1, P2, and P3, asin the two preceding example variants according to FIGS. 9 and 10, arenow axially arranged in a changed sequence. Thus, the mounting interfaceGW1-A of the first input shaft GW1 is initially followed by the secondplanetary gear set P2, then the third planetary gear set P3, and,finally, the first planetary gear set P1. While the shift elements A andF combined to form the shift element pair SP1 are situated axiallybetween the third planetary gear set P3 and the first planetary gear setP1, the remaining shift elements B, C, D, and E are located axially on aside of the first planetary gear set P1 facing away from the thirdplanetary gear set P3. In this case, the fourth shift element D issituated axially adjacent to the first planetary gear set P1, wherein,positioned subsequent thereto, are, initially, the fifth shift elementE, then the second shift element B, and, finally, the third shiftelement C. Once again, the fourth shift element D and the fifth shiftelement E are combined to form the shift element pair SP3, and thesecond shift element B and the third shift element C are combined toform the shift element pair SP2. The electric machine EM1 is arrangedaxially largely at the level of the third planetary gear set P3 and ofthe first planetary gear set P1 and radially surrounding theseOtherwise, the example variant according to FIG. 11 corresponds to theexample embodiment according to FIG. 8, and therefore reference is madeto the description thereof.

FIG. 12 shows a diagrammatic view of a transmission G according to aneleventh example design option of the invention. This example designoption can also be utilized in the motor vehicle drive train in FIG. 1and essentially corresponds to the example variant according to FIG. 9,wherein, in contrast to the example variant according to FIG. 9, afurther shift element H is now additionally provided, which, uponactuation, connects the first input shaft GW1 to the first element E13of the third planetary gear set P3 in a rotationally fixed manner. Thisfurther shift element H, which is also designed as a form-locking shiftelement, is provided axially between the mounting interface GW1-A of thefirst input shaft GW1 and the first shift element A. Otherwise, theexample design option according to FIG. 12 corresponds to the examplevariant according to FIG. 9, and therefore reference is made to thedescription thereof.

FIG. 13 shows an exemplary shift pattern for the transmissions G fromFIGS. 2 through 12 in table form. As is apparent, a total of four gears1 through 4, which differ in terms of the ratio, and one auxiliary gearHZG can be implemented between the first input shaft GW1 and the outputshaft GWA, wherein, in the columns of the shift pattern, an X indicateswhich of the shift elements A through F is engaged in which of the gears1 through 4 and in the auxiliary gear HZG.

As is apparent in FIG. 13, a first gear 1 is engaged between the firstinput shaft GW1 and the output shaft GWA by actuating the first shiftelement A and the fifth shift element E. Moreover, a second gear 2results between the first input shaft GW1 and the output shaft GWA byengaging the first shift element A and the fourth shift element D. Inaddition, a third gear can be implemented between the first input shaftGW1 and the output shaft GWA in a first variant 3.1 by actuating thefirst shift element A and the second shift element B, wherein the thirdgear can also be implemented in a second variant 3.2 by engaging thesecond shift element B and the sixth shift element F, in a third variant3.3 by actuating the fourth shift element D and the sixth shift elementF, in a fourth variant 3.4 by engaging the second shift element B andthe fourth shift element D, in a fifth variant 3.5 by actuating thesecond shift element B and the fifth shift element E, and in a sixthvariant 3.6 by engaging the second shift element B. While the electricmachine EM1 is also integrated in each of the variants 3.1 through 3.5,and so travel can take place in a hybrid manner while simultaneouslyutilizing the internal combustion engine VKM and the electric machineEM1, the electric machine EM1 is decoupled in the case of the sixthvariant 3.6. The latter has the advantage that the electric machine EM1does not need to be engaged during operation.

In addition, a fourth gear results between the first input shaft GW1 andthe output shaft GWA in a first variant 4.1 by actuating the first shiftelement A and the third shift element C, wherein the fourth gear canalso be engaged in a second variant 4.2 by engaging the third shiftelement C and the sixth shift element F, in a third variant 4.3 byactuating the third shift element C and the fourth shift element D, in afourth variant 4.4 by engaging the third shift element C and the fifthshift element E, and in a fifth variant 4.5 by actuating the third shiftelement C. In the final, fifth variant 4.5, the electric machine EM1 isdecoupled, and so travel can take place purely via the upstream internalcombustion engine VKM. By comparison, in the variants 4.1 through 4.4,travel takes place in a hybrid manner with simultaneous utilization ofthe internal combustion engine VKM and the electric machine EM1.Finally, the auxiliary gear HZG results by engaging the fifth shiftelement E and the sixth shift element F.

Although the shift elements A through F are each designed as form-fitshift elements, a power shift can be implemented between the first gear1 and the second gear 2, between the second gear 2 and the first variant3.1 of the third gear, and between the first variant 3.1 of the thirdgear and the first variant 4.1 of the fourth gear. The reason thereforis that the first shift element A contributes to all these gears. Asynchronization during the gear shifts can take place in each case viaan appropriate closed-loop control of the upstream internal combustionengine VKM, and therefore the particular shift element to be disengagedis disengaged without load and the shift element to be subsequentlyengaged can be engaged without load.

The transmissions G from FIGS. 2 through 12 can also be operated inalternative operating modes with the aid of the electric machine EM1.Purely electric driving can take place in a first gear E1, which iseffective between the second input shaft GW2 and the output shaft GWAand, for the implementation of which, the first shift element A is to betransferred into an engaged condition. As a result, when the first shiftelement A is engaged, the electric machine EM1 is coupled to the outputshaft GWA via the second planetary gear set P2 and the third planetarygear set P3, wherein the ratio of the first gear E1 corresponds to aratio of the first gear 1 between the first input shaft GW1 and theoutput shaft GWA.

In addition, a second gear E2 can also be implemented between the secondinput shaft GW2 and the output shaft GWA, for the implementation ofwhich the sixth shift element F is to be engaged. As a result, theoutput shaft GWA is then coupled via the second planetary gear set P2 tothe second input shaft GW2 and, thereby, also to the rotor R1 of theelectric machine EM1. A ratio of this second gear E2 corresponds to aratio of the auxiliary gear HZG, which is effective between the firstinput shaft GW1 and the output shaft GWA.

Advantageously, starting from the first gear El, a start of the internalcombustion engine VKM can take place into the first gear 1, into thesecond gear 2, into the first variant 3.1 of the third gear, or into thefirst variant 4.1 of the fourth gear, since the first shift element A isalso engaged in each of these gears. The same is possible from thesecond gear E2 into the gears 3.2, 3.3, 4.2, and HZG, since the sixthshift element F also contributes to each of these. Therefore, atransition from purely electric driving into driving via the internalcombustion engine or into hybrid driving can be carried out rapidly.

Moreover, a charging or starting function can be implemented by engagingthe fourth shift element D. This is the case because, in the engagedcondition of the fourth shift element D, the second input shaft GW2 iscoupled via the second planetary gear set P2 to the first input shaftGW1 and, thereby, also to the internal combustion engine VKM.Simultaneously, there is no force-fit connection to the output shaftGWA, however, wherein the second input shaft GW2 rotates faster than thefirst input shaft GW1 in this case. When the electric machine EM1 isoperated as a generator, an electric accumulator can be charged via theinternal combustion engine VKM, whereas, when the electric machine EM1is operated as an electric motor, a start of the internal combustionengine VKM is implementable via the electric machine EM1.

Alternatively, however, a charging or starting function can also beimplemented by engaging the fifth shift element, wherein, in this case,the first input shaft GW1 and the second input shaft GW2 are thendirectly connected to each other in a rotationally fixed manner, and sothe rotor R1 of the electric machine EM1 is also directly connected tothe first input shaft GW1 in a rotationally fixed manner. In this case,the electric machine EM1 can be operated as a generator or as anelectric motor.

In addition, a rotational-speed reduction of the electric machine EM1can be configured in the mechanical or hybrid mode. After a gear shiftfrom the third gear into the fourth gear, with torque support via theelectric machine EM1, or after a start of the internal combustion engineVKM into the fourth gear, hybrid driving in the first variant 4.1 of thefourth gear results. In order to reduce the rotational speed of theelectric machine EM in the fourth gear at higher ground speeds, achange-over can be carried out from the first variant 4.1 of the fourthgear into the second variant 4.2, in which the rotor R1 has a lowerrotational speed. This change-over takes place while obtaining thetractive force via the internal combustion engine VKM with the thirdshift element C engaged. For this purpose, the first shift element A,which is then load-free, is disengaged and the likewise load-free, sixthshift element F is engaged, wherein the rotational-speed adaptationtakes place in each case via closed-loop control of the rotational speedof the electric machine EM.

The change-over into the second variant 4.2 also has the advantage thatthe internal combustion engine VKM can be decoupled at any time bydisengaging the third shift element C also in the absence of anadditional separating clutch, while the electric machine EM1 drives ordecelerates the vehicle. Moreover, in the case of a vehicle that isslowing down, a downshift from the fourth gear into the third gear canbe prepared, in that, initially, a change-over takes place from thesecond variant 4.2 into the first variant 4.1, while the internalcombustion engine VKM maintains the tractive force with the third shiftelement C engaged. In the first variant 4.1 of the fourth gear, thefirst shift element A is engaged, which becomes necessary in order tosupport the tractive force via the electric machine EM1 during thedownshift from the fourth gear into the third gear. Alternatively, adownshift can also be implemented from the second variant 4.2 of thefourth gear into the second variant 3.2 of the third gear, however,since the sixth shift element F contributes to both of these.

In addition, an electrodynamic starting function can be implemented withthe transmission G from FIG. 12. For this purpose, the further shiftelement H is to be engaged, wherein, in this case, the upstream internalcombustion engine VKM is then connected to the first element E13 of thethird planetary gear set P3, while the electric machine EM1 is connectedvia the constant ratio of the second planetary gear set to the thirdelement E33 of the third planetary gear set P3 and the output shaft GWAis connected to the second element E23 of the third planetary gear setP3. A ratio results for the internal combustion engine VKM that ishigher than the ratio of the first gear 1.

Moreover, FIG. 14 shows a schematic of a transmission G according to atwelfth example embodiment of the invention, of the type which can alsobe utilized in the motor vehicle drive train in FIG. 1. This exampleembodiment essentially corresponds to the example variant according toFIG. 2, wherein, in contrast thereto, the first input shaft GW1 can nowbe rotationally fixed, at the mounting interface GW1-A via a seventhshift element K0, to a connection shaft AN, which is then connected tothe upstream internal combustion engine VKM in the motor vehicle drivetrain. The seventh shift element K0 is configured as a form-lockingshift element and, particularly preferably, is present as aconstant-mesh shift element. Moreover, a further electric machine EM2 isalso provided, the rotor R2 of which is rotationally fixed to the firstinput shaft GW1, while a stator S2 of the further electric machine EM2is fixed at the rotationally fixed component GG. The rotor R2 isconnected at the first input shaft GW1 axially between the seventh shiftelement K0 and the second shift element B. For the rest, the examplevariant according to FIG. 14 corresponds to the example design optionaccording to FIG. 2, and therefore reference is made to the descriptionthereof.

FIG. 15 shows a diagrammatic view of a transmission G according to athirteenth example design option of the invention. This example designoption can also be utilized in the motor vehicle drive train from FIG.1, wherein the example design option largely corresponds to the examplevariant from FIG. 12. The difference now, however, is that the firstinput shaft GW1 can be connected, at the mounting interface GW1-A, as isalso the case in the preceding example variant according to FIG. 14, viaa seventh shift element K0 in a rotationally fixed manner to aconnection shaft AN, which is then connected to the upstream internalcombustion engine VKM in the motor vehicle drive train. In this case,the seventh shift element K0 is designed as a form-locking shift elementand, in this case, preferably as a constant-mesh shift element. Inaddition, a further electric machine EM2 is also provided, the rotor R2of which is rotationally fixed to the first input shaft, while a statorS2 of the further electric machine EM2 is fixed at the rotationallyfixed component GG. A connection of the rotor R2 of the further electricmachine EM2 at the first input shaft GW1 is implemented axially betweenthe seventh shift element K0 and the further shift element H. Otherwise,the example variant according to FIG. 15 corresponds to the exampleembodiment according to FIG. 12, and therefore reference is made to thedescription thereof.

In FIG. 16, different conditions I through XXX of the motor vehicledrive train from FIG. 1, with utilization of the transmission G fromFIG. 14 or 15, are represented in table form, wherein these differentconditions I through XXX are achieved via different integrations of thetwo electric machines EM1 and EM2 and the internal combustion engineVKM. Overall, thirty different conditions I through XXX can berepresented. In the subsequent columns, it is indicated which of thegears with respect to the electric machine EM1, with respect to thefurther electric machine EM2, and also with respect to the internalcombustion engine VKM are selected in the transmission G, wherein 0means that no connection and/or no independent connection of theparticular electric machine EM1 and/or EM2 and/or of the internalcombustion engine VKM to the output shaft GWA has been established.

In a first condition I, purely electric driving takes place via theelectric machine EM1, in that, in the transmission G, the first gear E1is selected in the way described above with respect to FIG. 13. In thecondition II as well, travel takes place solely via the electric machineEM1, wherein, for this purpose, the second gear E2 is selected in thetransmission G, which results via the sole actuation of the sixth shiftelement F. By comparison, in the condition III, operation takes placevia the further electric machine EM2, in that the sixth variant 3.6 ofthe third gear is selected in the transmission G in the way describedwith respect to FIG. 13. Likewise, in the condition IV, travel takesplace solely via the further electric machine EM2, wherein, for thispurpose, the fifth variant 4.5 of the fourth gear is selected in thetransmission G by engaging the third shift element C. In the conditionsI through IV, travel can take place in a particularly effective manner,since, in the case of a low load request, travel takes place via onlyone of the two electric machines EM1 or EM2.

Starting at the condition V through the condition XVI, travel takesplace via the electric machine EM1 as well as the further electricmachine EM2, in that both electric machines EM1 and EM2 are jointlyincorporated via the selection of the appropriate gears in thetransmission G. Thus, in the condition V, the first gear El and thefirst gear 1 are selected; in the condition VI, the first gear E1 andthe second gear 2 are selected; in the condition VII, the first gear E1and the first variant 3.1 of the third gear are selected; in thecondition VIII, the second gear E2 and the second variant 3.2 of thethird gear are selected; in the condition IX, the second gear E2 and thethird variant 3.3 of the third gear are selected; in the condition X,the fourth variant 3.4 of the third gear is selected; in the conditionXI, the fifth variant 3.5 of the third gear is selected; in thecondition XII, the first gear E1 and the first variant 4.1 of the fourthgear are selected; in the condition XIII, the second gear E2 and thesecond variant 4.2 of the fourth gear are selected; in the conditionXIV, the third variant 4.3 of the fourth gear is selected; in thecondition XV, the fourth variant 4.4 of the fourth gear is selected;and, in the condition XVI, the second gear E2 and the auxiliary gear EZGare selected. In the conditions X, XI, XIV, and XV, the electric machineEM1 is not independently coupled to the output shaft GWA, but rather tothe first input shaft GW1 via the fourth shift element D and/or thefifth shift element E, and so the electric machine EM1 can support adrive motion.

In the conditions XVII through XXX, travel then takes place in a hybridmanner by utilizing both electric machines EM1 and EM2 as well as theinternal combustion engine VKM, in that the latter is engaged byengaging the fifth shift element K0 in each case. A synchronization ofthe fifth shift element K0 is implemented, in particular, via thefurther electric machine EM2. With regard to the selection of the gears,the conditions XVII through XXIII, XXV through XXVIII and XXX correspondto the conditions V through XVI, with the difference that now the fifthshift element K0 is to be engaged in each case. The representation ofthe individual gears is shown in the columns for the individual shiftelements A, B, C, D, E, and F and is specifically described withreference to FIG. 13. In the conditions XXIV and XXIX, however, theelectric machine EM1 is decoupled.

In the transmission G according to FIG. 15, in addition, a powershiftability of the electric gears E1 and E2 can also be implemented viathe further shift element H, with the advantage that the electricmachine EM1 also contributes the largest portion of the drive powerduring the gear shifts and the further electric machine EM2 cantherefore be made considerably smaller. In addition to theelectrodynamic starting operation described with respect to FIG. 12, apurely electric starting operation can also be made possible with thetransmission according to FIG. 15, wherein the seventh shift element K0must be in a disengaged condition and the further shift element H isengaged. This has the advantage that travel can also take place for alonger time with high torque and very low ground speeds, without theelectric machines or an inverter overheating, since both electricmachines EM1 and EM2 can be operated at suitable rotational speeds.

Finally, FIGS. 17 through 22 show example modifications of thetransmissions G from FIGS. 2 through 12 as well as 14 and 15. Theseexample modifications relate to alternative possibilities forintegrating the electric machine EM1, although the example modificationscan also be utilized, in a similar way, for the further electric machineEM2 in the transmissions G according to FIGS. 14 and 15. In FIG. 17, forexample, the electric machine EM1 is not located coaxially to theparticular gear set RS (not represented in greater detail here) of thetransmission G, but rather is arranged axially offset with respectthereto. A connection takes place via a spur gear stage SRS, which iscomposed of a first spur gear SR1 and a second spur gear SR2. The firstspur gear SR1 is connected at the second input shaft GW2 in arotationally fixed manner on the side of the particular gear set RS. Thespur gear SR1 then meshes with the spur gear SR2, which is located on aninput shaft EW of the electric machine EM1 in a rotationally fixedmanner. Within the electric machine EM1, the input shaft EW establishesthe connection at the rotor (not represented further in this case) ofthe electric machine EM1.

In the case of the example modification according to FIG. 18 as well,the electric machine EM1 is located axially offset with respect to theparticular gear set RS of the particular transmission G. In contrast tothe preceding example variant according to FIG. 17, a connection is notestablished in this case via a spur gear stage SRS, however, but rathervia a flexible traction drive mechanism ZT. This flexible traction drivemechanism ZT can be configured as a belt drive or also a chain drive.The flexible traction drive mechanism ZT is then connected at the secondinput shaft GW2 on the side of the particular gear set RS. Via theflexible traction drive mechanism ZT, a coupling to an input shaft EW ofthe electric machine EM1 is then established. Within the electricmachine EM1, the input shaft EW establishes a connection at the rotor ofthe electric machine.

In the case of the example modification according to FIG. 19, anintegration of the electric machine EM1, which is located axially offsetwith respect to the particular gear set RS, is implemented via aplanetary gear stage PS and a spur gear stage SRS. The planetary gearstage PS is connected downstream from the gear set RS, wherein, on theoutput end of the planetary gear stage PS, the spur gear stage SRS isthen provided, via which the connection to the electric machine EM1 isestablished. The planetary gear stage PS is composed of a ring gear HO,a planet carrier PT, and a sun gear SO, wherein the planet carrier PTguides, in a rotatably mounted manner, at least one planet gear PR,which is meshed with the sun gear SO as well as with the ring gear HO.

In the present case, the planet carrier PT is connected at the secondinput shaft GW2 in a rotationally fixed manner on the side of the gearset RS from FIGS. 2 through 12 as well as 14 and 15. By comparison, thering gear HO is permanently fixed at the rotationally fixed componentGG, while the sun gear SO is rotationally fixed to a first spur gear SR1of the spur gear stage SRS. The first spur gear SR1 then intermesheswith a second spur gear SR2 of the spur gear stage SRS, which isprovided, in a rotationally fixed manner, on an input shaft EW of theelectric machine EM1. In this case, the electric machine EM1 istherefore connected by the gear set RS via two gear stages.

In the case of the example modification from FIG. 20 as well, anintegration of the electric machine EM1 is implemented by the gear setRS via a planetary gear stage PS and a spur gear stage SRS. Themodification largely corresponds to the example variant according toFIG. 19, with the difference that, with respect to the planetary gearstage PS, the sun gear SO is now fixed at the rotationally fixedcomponent GG, while the ring gear HO is rotationally fixed to the firstspur gear SR1 of the spur gear stage SRS. Specifically, the ring gear HOand the first spur gear SR1 are preferably designed as one piece, inthat the ring gear HO is equipped, at an outer circumference, with atooth system. For the rest, the example modification according to FIG.20 corresponds to the example variant according to FIG. 19, andtherefore reference is made to the description thereof.

Moreover, FIG. 21 shows one further example modification of thetransmissions G from FIGS. 2 through 12 as well as 14 and 15, wherein,in this case as well, an integration of the electric machine EM1 isimplemented via a spur gear stage SRS and a planetary gear stage PS. Incontrast to the preceding example variant according to FIG. 20, the gearset RS is initially followed here by the spur gear stage SRS, while theplanetary gear stage PS is provided in the power flow between the spurgear stage SRS and the electric machine EM1. The planetary gear stage PSalso includes, once again, the elements ring gear HO, planet carrier PT,and sun gear SO, wherein the planet carrier PT guides, in a rotatablymounted manner, multiple planet gears PR1 and PR2, each of which ismeshed with the sun gear SO as well as with the ring gear HO.

As is apparent in FIG. 21, a first spur gear SR1 of the spur gear stageSRS is connected in a rotationally fixed manner on the side of the gearstage RS of the transmissions G from FIGS. 2 through 12 as well as 14and 15, wherein this connection is completed at the second input shaftGW2. The first spur gear SR1 then intermeshes with a second spur gearSR2 of the spur gear stage SRS, which is rotationally fixed to theplanet carrier PT of the planetary gear stage PS. The ring gear HO ispermanently fixed at the rotationally fixed component GG, while the sungear SO is provided, in a rotationally fixed manner, on an input shaftEW of the electric machine EM1.

Finally, FIG. 22 shows one further example modification of thetransmissions G from FIGS. 2 through 12 as well as 14 and 15, whereinthis example modification essentially corresponds to the precedingexample variant according to FIG. 21. The only difference is that thesun gear SO of the planetary gear stage PS is now permanently fixed atthe rotationally fixed component GG, while the ring gear HO of theplanetary gear stage PS is rotationally fixed to the input shaft EW ofthe electric machine EM1. For the rest, the example modificationaccording to FIG. 22 corresponds to the example variant according toFIG. 20, and therefore reference is made to the description thereof.

By means of the embodiments according to the invention, a transmissionhaving a compact design and good efficiency can be implemented.

Modifications and variations can be made to the embodiments illustratedor described herein without departing from the scope and spirit of theinvention as set forth in the appended claims. In the claims, referencecharacters corresponding to elements recited in the detailed descriptionand the drawings may be recited. Such reference characters are enclosedwithin parentheses and are provided as an aid for reference to exampleembodiments described in the detailed description and the drawings. Suchreference characters are provided for convenience only and have noeffect on the scope of the claims. In particular, such referencecharacters are not intended to limit the claims to the particularexample embodiments described in the detailed description and thedrawings.

REFERENCE CHARACTERS

-   G transmission-   RS gear set-   GG rotationally fixed component-   P1 first planetary gear set-   E11 first element of the first planetary gear set-   E21 second element of the first planetary gear set-   E31 third element of the first planetary gear set-   P2 second planetary gear set-   E12 first element of the second planetary gear set-   E22 second element of the second planetary gear set-   E32 third element of the second planetary gear set-   P3 third planetary gear set-   E13 first element of the third planetary gear set-   E23 second element of the third planetary gear set-   E33 third element of the third planetary gear set-   A first shift element-   B second shift element-   C third shift element-   D fourth shift element-   E fifth shift element-   F sixth shift element-   H further shift element-   K0 seventh shift element-   SP1 shift element pair-   SP2 shift element pair-   SP3 shift element pair-   1 first gear-   2 second gear-   3.1 third gear-   3.2 third gear-   3.3 third gear-   3.4 third gear-   3.5 third gear-   3.6 third gear-   4.1 fourth gear-   4.2 fourth gear-   4.3 fourth gear-   4.4 fourth gear-   4.5 fourth gear-   HZG auxiliary gear-   E1 first gear-   E2 second gear-   GW1 first input shaft-   GW1-A mounting interface-   GW2 second input shaft-   GWA output shaft-   GWA-A mounting interface-   AN connection shaft-   EM1 electric machine-   S1 stator-   R1 rotor-   EM2 electric machine-   S2 stator-   R2 rotor-   SRS spur gear stage-   SR1 spur gear-   SR2 spur gear-   PS planetary gear stage-   HO ring gear-   PT planet carrier-   PR planet gear-   PR1 planet gear-   PR2 planet gear-   SO sun gear-   ZT flexible traction drive mechanism-   VKM internal combustion engine-   TS torsional vibration damper-   AG differential gear-   DW driving wheels-   I through XXX conditions

1-18. (canceled)
 19. A transmission (G) for a motor vehicle, comprising:an electric machine (EM1); a first input shaft (GW1); a second inputshaft (GW2); an output shaft (GWA); a first planetary gear set (P1), asecond planetary gear set (P2), and a third planetary gear set (P3),each of the first, second, and third planetary gear sets (P1, P2, P3)respectively comprising a first element (E11, E21, E31), a secondelement (E12, E22, E32), and a third element (E13, E23, E33); and aplurality of shift elements comprising a first shift element (A), asecond shift element (B), a third shift element (C), a fourth shiftelement (D), a fifth shift element (E), and a sixth shift element (F),wherein a rotor (R1) of the electric machine (EM1) is connected to thesecond input shaft (GW2), wherein the first input shaft (GW1) isrotationally fixed to the second element (E21) of the first planetarygear set (P1), wherein the output shaft (GWA) is rotationally fixed tothe third element (E31) of the first planetary gear set (P1), whereinthe second input shaft (GW2) is connected in a rotationally fixed mannerto the third element (E32) of the second planetary gear set (P2),wherein the first element (E12) of the second planetary gear set (P2) isfixed, wherein two of the first, second, and third elements (E11, E21,E31) of the first planetary gear set (P1) are connectable to each otherin a rotationally fixed manner via the second shift element (B), whereinthe first element (E11) of the first planetary gear set (P1) is fixableby the third shift element (C), wherein the second element (E22) of thesecond planetary gear set (P2) is bringable into a rotationally fixedconnection with the first input shaft (GW1) via the fourth shift element(D), and wherein the first input shaft (GW1) is connectable to thesecond input shaft (GW2) in a rotationally fixed manner by the fifthshift element (E).
 20. The transmission (G) of claim 19, wherein: thefirst element (E13) of the third planetary gear set (P3) is fixable viathe first shift element (A); the second element (E23) of the thirdplanetary gear set (P3) is rotationally fixed to the output shaft (GWA);the third element (E33) of the third planetary gear set (P3) isconnected to the second element (E22) of the second planetary gear set(P2) in a rotationally fixed manner; and the sixth shift element (F) isoperable to selectively connect the first element (E13) of the thirdplanetary gear set (P3) to the second element (E23) of the thirdplanetary gear set (P3) a rotationally fixed manner, or the firstelement (E13) of the third planetary gear set (P3) to the third element(E33) of the third planetary gear set (P3) in a rotationally fixedmanner, or the second element (E23) of the third planetary gear set (P3)to the third element (E33) of the third planetary gear set (P3) in arotationally fixed manner.
 21. The transmission (G) of claim 20,wherein, by selectively engaging the plurality of shift elements (A, B,C, D, E, F): a first gear (1) results between the first input shaft(GW1) and the output shaft (GWA) by actuating the first shift element(A) and the fifth shift element (E); a second gear (2) results betweenthe first input shaft (GW1) and the output shaft (GWA) by engaging thefirst shift element (A) and the fourth shift element (D); a third gearresults between the first input shaft (GW1) and the output shaft (GWA)in a first variant (3.1) by actuating the first shift element (A) andthe second shift element (B), in a second variant (3.2) by engaging thesecond shift element (B) and the sixth shift element (F), in a thirdvariant (3.3) by actuating the fourth shift element (D) and the sixthshift element (F), in a fourth variant (3.4) by engaging the secondshift element (B) and the fourth shift element (D), in a fifth variant(3.5) by actuating the second shift element (B) and the fifth shiftelement (E), and in a sixth variant (3.6) by engaging the second shiftelement (B); a fourth gear results between the first input shaft (GW1)and the output shaft (GWA) in a first variant (4.1) by actuating thefirst shift element (A) and the third shift element (C), in a secondvariant (4.2) by engaging the third shift element (C) and the sixthshift element (F), in a third variant (4.3) by actuating the third shiftelement (C) and the fourth shift element (D), in a fourth variant (4.4)by engaging the third shift element (C) and the fifth shift element (E),and in a fifth variant (4.5) by actuating the third shift element (C);and an auxiliary gear (HZG) results by engaging the fifth shift element(E) and the sixth shift element (F).
 22. The transmission (G) of claim19, wherein: the second element (E22) of the second planetary gear set(P2) is rotationally fixable to the output shaft (GWA) via the sixthshift element (F); with respect to the third planetary gear set (P3),there is a first coupling of the first element (E13) of the thirdplanetary gear set (P3) to a rotationally fixed component (GG), a secondcoupling of the second element (E23) of the third planetary gear set(P3) to the output shaft (GWA), and a third coupling of the thirdelement (E33) of the third planetary gear set (P3) to the second element(E22) of the second planetary gear set (P2); two of the first, second,and third couplings are permanently rotationally fixed connections, anda rotationally fixed connection is implementable for the remaining oneof the first, second, and third couplings via the first shift element(A).
 23. The transmission (G) of claim 22, wherein, by selectivelyengaging the plurality of shift elements (A, B, C, D, E, F): a firstgear (1) results between the first input shaft (GW1) and the outputshaft (GWA) by actuating the first shift element (A) and the fifth shiftelement (E); a second gear (2) results between the first input shaft(GW1) and the output shaft (GWA) by engaging the first shift element (A)and the fourth shift element (D); a third gear results between the firstinput shaft (GW1) and the output shaft (GWA) in a first variant (3.1) byactuating the first shift element (A) and the second shift element (B),in a second variant (3.2) by engaging the second shift element (B) andthe sixth shift element (F), in a third variant (3.3) by actuating thefourth shift element (D) and the sixth shift element (F), in a fourthvariant (3.4) by engaging the second shift element (B) and the fourthshift element (D), in a fifth variant (3.5) by actuating the secondshift element (B) and the fifth shift element (E), and in a sixthvariant (3.6) by engaging the second shift element (B); a fourth gearresults between the first input shaft (GW1) and the output shaft (GWA)in a first variant (4.1) by actuating the first shift element (A) andthe third shift element (C), in a second variant (4.2) by engaging thethird shift element (C) and the sixth shift element (F), in a thirdvariant (4.3) by actuating the third shift element (C) and the fourthshift element (D), in a fourth variant (4.4) by engaging the third shiftelement (C) and the fifth shift element (E), and in a fifth variant(4.5) by actuating the third shift element (C); and an auxiliary gear(HZG) results by engaging the fifth shift element (E) and the sixthshift element (F).
 24. The transmission (G) of claim 19, wherein: afirst gear (E2) results between the second input shaft (GW2) and theoutput shaft (GWA) by engaging the first shift element (A); and a secondgear (E2) results between the second input shaft (GW2) and the outputshaft (GWA) by actuating the sixth shift element (F).
 25. Thetransmission (G) of claim 19, further comprising an additional electricmachine (EM2), a rotor (R2) of the additional electric machine (EM2)connected at the first input shaft (GW1).
 26. The transmission (G) ofclaim 19, wherein the plurality of shift elements further comprises aseventh shift element (K0), the first input shaft (GW1) is rotationallyfixable to a connecting shaft (AN) via the seventh shift element (K0).27. The transmission (G) of claim 19, wherein the plurality of shiftelements further comprises a further shift element (H), the first inputshaft (GW1) rotationally fixable to the first element (E13) of the thirdplanetary gear set (P3) via the further shift element (H).
 28. Thetransmission (G) of claim 19, wherein one or more of the plurality ofshift elements (A, B, C, D, E, F; A, B, C, D, E, F, H; A, B, C, D, E, F,K0; A, B, C, D, E, F, H, K0) is a form-locking shift element.
 29. Thetransmission (G) of claim 19, wherein one or more of the first, second,and third planetary gear sets (P1, P2, P3) is a minus planetary gearset, the respective first element (E11, E12, E13) of the one or more ofthe first, second, and third planetary gear sets (P1, P2, P3) is arespective sun gear, the respective second element (E21, E22, E23) ofthe one or more of the first, second, and third planetary gear sets (P1,P2, P3) is a respective planet carrier, and the respective third element(E31, E32, E33) of the one or more of the first, second, and thirdplanetary gear sets (P1, P2, P3) is a respective ring gear.
 30. Thetransmission of claim 19, wherein one or more of the first, second, andthird planetary gear sets (P1, P2, P3) is a plus planetary gear set, therespective first element of the of the one or more of the first, second,and third planetary gear sets (P1, P2, P3) is a respective sun gear, therespective second element of the of the one or more of the first,second, and third planetary gear sets (P1, P2, P3) is a respective ringgear, and the respective third element of the of the one or more of thefirst, second, and third planetary gear sets (P1, P2, P3) is arespective planet carrier.
 31. The transmission (G) of claim 19, whereinthe first shift element (A) and the sixth shift element (F) are combinedto form a shift element pair (SP1) with an associated actuating element,and either the first shift element (A) or the sixth shift element (F) isactuatable from a neutral position via the actuating element.
 32. Thetransmission (G) of claim 19, wherein the second shift element (B) andthe third shift element (C) are combined to form a shift element pair(SP2) with an associated actuating element, and either the second shiftelement (B) or the third shift element (C) is actuatable from a neutralposition via the actuating element.
 33. The transmission (G) of claim19, wherein the fourth shift element (D) and the fifth shift element (E)are combined to form a shift element pair (SP3) with which an associatedactuating element, and either the fourth shift element (D) or the fifthshift element (E) is actuatable from a neutral position via theactuating element.
 34. The transmission (G) of claim 19, wherein therotor (R1) of the electric machine (EM1) is rotationally fixed to thesecond input shaft (GW2) or is connected to the second input shaft (GW2)via at least one gear stage.
 35. A motor vehicle drive train for ahybrid or electric vehicle, comprising the transmission (G) of claim 19.36. A method for operating the transmission (G) of claim 19, whereinonly the fourth shift element (D) or the fifth shift element (E) isengaged in order to implement a charging operation or a startingoperation.
 37. A method for operating the transmission (G) of claim 27,wherein the further shift element (H) is engaged in order to implement astarting mode for forward travel during driving via the input shaft(GW1).